Visions for Kimball Creek
December 2002
University of Washington
Institute for Hazards Mitigation Planning and Research
Vision Steps for Kimball Creek Page i
Visions for Kimball Creek
December 2002
A Report to the City of Snoqualmie
Autumn 2002 Floodplain Management and Stream Ecology Studio, University of Washington Institute for Hazards Mitigation Planning and Research, Department of Urban Design and Planning
Professors
Bob Freitag
Frank Westerlund
Students
Rebekkah Coburn
Lorelei Juntunen
Ingrid Lundin
Jason Scully
John Walsh
Matthew Wiley
University of Washington
Institute for Hazards Mitigation Planning and Research
Vision Steps for Kimball Creek Page ii
Executive Summary
Introduction and Background
Kimball Creek, a tributary of the Snoqualmie River, and the Snoqualmie River itself surround the City of Snoqualmie. Kimball Creek, together with its wetlands and tributaries, shapes the physical landscape of the City of Snoqualmie. The stream corridor winds through the community’s parks, neighborhoods, and backyards on its path to the Snoqualmie River. While much research has been conducted to determine Snoqualmie River’s ecological health and flooding risk, little attention has been focused on Kimball Creek. Despite the fact that the length of the creek is within the city’s urban growth area, the creek is not recognized as a community asset; many residents of the city may not even realize that the creek exists. The waters of Kimball Creek have relatively high levels of fecal coliform, are surrounded mostly by blackberries, flood often, and are nearly inaccessible to the residents of the City of Snoqualmie.
This project considers Kimball Creek to be an unexplored opportunity for the City of Snoqualmie. Ideally, this document and the vision within it will serve as a starting point for a broad, community-based planning process focusing on the corridor as an asset.
Responding to ecological, flood risk, and human use aspects of Kimball Creek, this document suggests measures of action that will lead to achieving the vision of the creek as an amenity for the entire community. Specific objectives for the creek include habitat restoration, water quality improvement, and flood safety. Overall, the project objective is to integrate Kimball Creek more deliberately into the community that surrounds it, making it a more visible, accessible, safe, and healthy resource for the people of Snoqualmie.
Work products include stream corridor and ecological maps depicting land cover and vegetation types, riparian buffer and bank conditions, corridor access points; the 10, 100, and 500 year flood event levels; recommendations for risk reduction and stream restoration; identification of restoration and management alternatives/opportunities for the Kimball Creek corridor, including a catalog and description of potential actions.
A Vision for Kimball Creek
The Kimball Creek corridor presents an opportunity for the City of Snoqualmie to think critically about its future. The City will continue to grow and develop in coming years. Without careful planning, this growth could negatively alter the community’s sense of identity. The vision described in this document is meant to be the beginning point for a community effort to address the Kimball Corridor as an asset for Snoqualmie’s future development. Through a concerted and deliberate planning effort, the Kimball Creek corridor can become an amenity for the entire community. Kimball Creek can be:
· A healthy, diverse ecosystem that provides habitat for wildlife even within a relatively urban setting. Through restoration, the creek would be cleaner, clearer, and colder, improving habitat for trout and other species.
· A focus of community involvement efforts, as volunteers come together to restore stability to the creeks banks and riparian habitat, and maintain trails that provide access to the creek. Kimball Creek would be an ideal tool for educators, youth and nature enthusiasts seeking an outdoor laboratory in a nearby wetland stream system.
· An accessible, integrated unit of the Snoqualmie community, and a place where residents and tourists can explore the scenic beauty of the area. Loops trails would connect existing trails to the Kimball corridor and the downtown core, creating opportunities for recreation while providing access to the creek’s natural habitat.
The following sections summarize some of the more pressing issues surrounding Kimball Creek and its development, providing appropriate actions to address these issues and move toward the achievement of the vision described above.
Stream Ecology
The Kimball Creek corridor has been significantly modified by development. The creek follows a historic meander of the Snoqualmie River, and drains wetlands, seeps, and streams throughout its length. Its history is characterized by flux, as its drainage is subjected to small-scale and large-scale flood events that alter the corridor, vegetation, and flow of the creek. Development has modified the structure and function of the stream corridor and the surrounding landscape.
This report assesses the condition of the Kimball Creek corridor and identifies areas where actions can improve the health of the stream. Restoration work along the stream corridor cannot hope to achieve pre-development conditions. However, restoration of various structural elements and ecological processes can improve the water quality, wildlife habitat, and overall ecological value of the stream corridor. Restoration proposals in this report include improvements to the landscape, to the riparian corridor, and to the active channel of the stream.
Water Quality
Historic water quality conditions in Kimball Creek are difficult to assess due to the lack of data collected on past stream conditions. Interviews with local residents indicate that Kimball Creek has shown a dramatic decrease in perceived water quality over the past 10 to 15 years, with the most noticeable decline in turbidity, or stream clarity. Comparison of aerial photography from 1949, 1971, and 2001 shows that the watershed has been subjected to development pressures and an associated decrease in forest and vegetation cover along the banks of Kimball Creek for at least 50 years. The loss of vegetative buffers along the Creek is often associated with declines in water quality.
Following are current measures of Kimball Creek’s water quality:
· Turbidity measures an average of 39.42 Nephelometric Turbidity Units (NTU) along the creek. (A clear flowing mountain stream is generally below 5.)
· Four out of the six test sites show fecal coliform numbers that could be harmful to people. Kimball Creek is in violation of the State Water Quality Standards for fecal coliform.
· Dissolved oxygen levels along Kimball Creek vary from test site to test site, but are generally inadequate to support fish populations.
Septic Systems
Aging septic systems (particularly in the Williams Addition) may be contributing to fecal coliform in Kimball Creek. Prevention of septic system failure should be addressed prior to development to prevent contamination of water sources. Steps that may be taken include: community education, setbacks from surface water and wells, stringent regulations for septic system siting, and large lot zoning. An initial determination of homes contributing directly to the water quality problem of Kimball Creek could be performed by providing dye tests to determine status of home septic systems.
Stormwater Management
While sources of sediment in Kimball Creek remain unidentified, the high turbidity measures are likely a combination of multiple non-point sources. Development practices in the watershed are probably contributing to sediment loads in the creek. Requiring new developments in the watershed to not simply divert storm water, but to treat and release at a rate that mimics natural base flows will increase the amount of water traveling through the system and increase the dilution and flushing rates of the Creek.
New construction in the Kimball Creek watershed should be closely monitored to insure compliance with all existing King County Storm Water Management practices.
Flooding Risk
Kimball Creek does not present a flood hazard on its own; however it does provide a corridor for overbank floodwaters from the Snoqualmie River. This results in a relatively significant risk of flooding for residents, especially those with homes near the confluence of Kimball Creek and the Snoqualmie River. Federal Emergency Management maps of the 100 year floodplain and the floodway do not adequately represent this pattern of flooding along Kimball Creek. Homes in the floodplain that are not elevated have suffered repetitive damages during the frequent floods in the area. Furthermore, floodway regulations, which restrict all new construction and do not allow for substantial improvement or rebuilding of damaged homes, present a hardship to the many Snoqualmie residents who own homes in the floodway overlay zone.
Split Floodway
Consider the feasibility of a split floodway, with the main conveyance channel along the Snoqualmie River, and a narrower channel along Kimball Creek. This land use change could open more land for development in the city’s core, most of which is currently zoned as “floodway overlay zone.” A split floodway could also limit development in the path of floodwaters as they have been documented, thereby more fully protecting life and property along Kimball Creek. The split floodway would preserve Kimball Creek as a corridor, protecting it permanently from future development, and, over time, opening more of the creek for public access and open space.
Elevation of Homes
Continue to encourage residents to elevate homes to above the base flood level, targeting especially those residents in the most frequently flooded areas along Kimball Creek. This is one of the most effective flood mitigation strategies available to those with homes in the floodplain.
Lot Buyouts
Continue to target repetitive loss homes for purchase. Strategically select those lots that would contribute most to the public good, and to maintenance of a corridor for public access and ecological integrity along Kimball Creek. Those include:
· Parcels bordering the creek. Public ownership of these parcels would provide further points of access to Kimball Creek, space for trails, and closer control of bank stability and habitat integrity.
· Parcels adjacent to existing buyouts. Contiguous plots would provide larger spaces for public parks and creek access.
· Parcels served by septic systems. Many of the septic systems in the area are older and may be in danger of failure. Reducing reliance on septic systems could have a positive effect on groundwater and stream water quality.
First Floor Elevation Database
Update and complete the first floor elevation database (with data usable in a GIS format) to prioritize those homes that should be targeted for future elevations and/or buyouts.
Human Use and Access
Kimball Creek is a community treasure, and should be considered as such. Its entire watercourse, from headwaters to mouth, lies within the city’s urban growth area. Wrapping around the city, it is inextricably linked to the biological health of the region. The creek’s dynamic relationships with biological and geological processes, combined with its location in the community, present major opportunities for the city of Snoqualmie. Currently, however, most of the creek runs through private property; the public can only access the creek from the few, small home buyout lots, at city and county right of ways, and at two parks (the Kimball Creek Nature Trail and Meadowbrook Park). At all of these locations, blackberries and other foliage make approaching the creek banks a challenge.
The creek could become an important part of the Snoqualmie community. First, the creek can become an important educational tool for communicating information about flooding events and creekside ecology. Second, the creek’s location can be used to create pedestrian connections to the various features the Snoqualmie region has to offer.
Citizen Committee
A citizen’s panel or committee should be created with the purpose of involving residents, area homeowners and outdoor enthusiasts in planning for the future use of the creek. This group would oversee a wide range of activities, including organizing volunteers, fund raising, outreach to local schools, and educating and gathering input from the public. The group could also take a leadership role in designing creekside trails and parks. The underlying goal of these activities would be for the group to strike a balance between the needs of the public and the neighborhoods surrounding the creek with efforts to preserve and enhance the creek’s ecological integrity.
Increase Public Access to Creek
Provide public access to creek, augment existing publicly owned lands, and strengthen positive public awareness for creek. This can be accomplished through strategic lot buyout, as outlined above: target parcels along the watercourse at high flood risk and that could become good locations for future parks or facilitate the expansion of existing parks. Increase positive public awareness for the creek through the creation and expansion of park space. Increase public ownership along creek at strategic points.
Create a Citywide Trail System
Create a citywide pedestrian, bicycle, and possibly equestrian trail system. Use the creek as a pedestrian path connecting the various features of Snoqualmie, and linking existing trails to the Kimball corridor. This would provide further public access, and add to public awareness of the creek as an asset.
The Future of Kimball Creek
All of these actions together could positively affect not just Kimball Creek, but the shape of the City of Snoqualmie in the years to come. The City is projected to grow rapidly; protecting open space and managing development within the urban growth area will help the city to maintain its rural character through the changes in infrastructure necessary to support a growing population. Planning for Kimball Creek as an asset now can be an important step in planning for a livable City of Snoqualmie in the future.
Visions for Kimball Creek Page 52
Table of Contents
Executive Summary i
Table of Contents vii
Chapter 1: Introduction and Background 1
Document Organization 1
Project Purpose and Objectives 2
Philosophy 2
Methods 2
Work Products 3
Location 4
Community Context 4
Chapter 2: Stream Ecology 7
Ecological Function of Kimball Creek 7
Assessment and Discussion 8
Surrounding Landscape 8
Riparian Area 8
Shading and Creek Temperature 9
Active Channel 10
Options for Stream Ecology Improvement 10
Surrounding Landscape 10
Riparian Area 10
Active Channel 11
Chapter 3: Water Quality 13
Past Conditions 13
Present Conditions Overview 13
Analysis of Water Quality 14
Septic Systems 16